Intake of whey protein as a supplement or in combination with resistance exercise, or as part of a weight-loss or weight-maintenance diet, may boost body composition for men and women, says a new meta-analysis of data from 14 randomized controlled trials.

Replacing calories in the diet with whey protein in a weight loss diet led to greater losses in body weight of 4.2 kg (9.2 lbs), on average, compared to baseline values, according to findings published in the Journal of the American College of Nutrition.

In addition, when whey protein was used in conjunction with resistance exercise participants had a statistically significant increase in lean body mass of 2.24 kg (4.9 lbs) on average, report researchers led by Dr Dominik Alexander from Exponent, Inc.

This research is supported by the Whey Protein Research Consortium. An earlier study by Dr David Baer, USDA, found that daily consumption of whey protein, but not soy protein, led to lower body weight, body fat and waist circumference compared to carbohydrates in free-living overweight and obese adults.

Bryan Helwig, PhD, Whey Protein Research Consortium, said: “These research findings support the Consortium's goal to create a strong scientific foundation demonstrating the health and wellness benefits of whey protein. This research provides further evidence demonstrating the benefits of whey proteins as they relate to body composition.”

Study details

Dr Alexander, Dr Paige Miller and Dr Vanessa Perez identified 14 RCTs with 626 participants for inclusion in their meta-analysis. The search was limited to RCTs with whey protein (concentrate, isolate, or hydrolystate), with or without resistance exercise, on body weight and body composition for generally healthy adults

Results showed that both body weight and body fat were significantly reduced when whey protein was used as a replacement for other sources of calories, with average decreases of 4.2 kg and 3.7 kg, respectively, compared with baseline values.

Furthermore, the benefits of whey protein tended to be more favorable when compared with carbohydrates than other (non-whey) protein sources. However, these differences did not reach statistical significance.

“The results indicate that there is something unique about whey protein, compared to other protein sources and carbohydrates, when it comes to building lean body mass and maintaining or losing weight,” said Dr Alexander.

Commenting on the potential mechanism, Bryan Helwig, PhD, Director of Protein Nutrition Research for the Dairy Research Institute, told us that the evidence clearly indicates that whey protein enhances muscle protein synthesis. “Additional research has also shown that during weight loss whey protein helps lose fat and maintain muscle,” he added. “However because this mechanism for this preservation of lean mass with body weight loss has not been clearly defined additional research is needed.”

Whey's ability to boost muscle protein synthesis is well established, linked to its high levels of the essential branched-chain amino acid leucine compared to alternative protein sources, added Dr Helwig. “Additionally, recent work has demonstrated that leucine as part of the amino acid profile of whey; helps maintain muscle protein synthesis over a period of 3 – 5 hours compared to supplemental leucine.”

Not only for bodybuilders…

Dr Helwig said that consumer awareness of whey protein’s benefits related to body composition is increasing.

“Consistent with this, consumers are also identifying that whey protein can be obtained in milk and yogurt in addition to powder form,” he said. “Once thought of solely as being for body builders, whey has become main stream and when consumed as part of a lifestyle that includes exercise can help individuals achieve body composition goals.”

Intake of whey protein as a supplement or in combination with resistance exercise, or as part of a weight-loss or weight-maintenance diet, may boost body composition for men and women, says a new meta-analysis of data from 14 randomized controlled trials.